> To: tutor@python.org
> From: __pete...@web.de
> Date: Sun, 10 Jan 2016 18:29:06 +0100
> Subject: Re: [Tutor] Question about the memory manager
>
> Albert-Jan Roskam wrote:
>
> > Hi,
> >
> > I just found a neat trick to free up an emergency stash of memory in a
> > funtion that overrides sys.excepthook. The rationale is that all
> > exceptions, including MemoryErrors will be logged. The code is below. My
> > question: is that memory *guaranteed* to be freed right after the 'del'
> > statement? Or should one call gc.collect to be really sure?
> >
> > rainydayfund = [[] for x in xrange(16*1024)] # or however much you need
> > def handle_exception(e):
> > global rainydayfund
> > del rainydayfund
> > ... etc, etc ...
> > http://stackoverflow.com/questions/1235349/python-how-can-i-handle-any-unhandled-exception-in-an-alternative-way
>
> I must admit that this looks rather strange to me, but I don't see any
> problem why it wouldn't work. gc.collect() only helps with circular
> dependencies, and there aren't any in your "rainy day fund".
>
> Regarding the use of sys.excepthook I'd rather (SO voting be damned!) take
> the obvious approach as suggested by Vinay Sajip, i. e.
>
> try:
> main()
> except:
> # do what you have to do
>
> instead of rewriting the hook. If potential memory resource hogs are
> confined within main() with no references from any module namespace you
> should have enough memory availaible to run the except suite without the
> need for a rainy day fund. If you know about a specific global name that
> references a consumer of a lot of memory, an in-memory db, say, then why not
> handle the memory error there or at least use it in lieu of a dedicated
> dummy? I. e.
>
> in_memory_db = None
> try:
> try:
> main()
> finally:
> del in_memory_db
> except:
> # do what you have to do
Hi all,
Thanks for your replies. Initially my main concern was to also log
fatal/unhandled exceptions. The database MemoryError was also I was also an
issue I was just facing, so Martelli's approach seemed nice. Meanwhile I found
out I did not only delete "TOP 100" (which I used to debug my code) in my
SELECT query, but also DISTINCT. After I corrected this MemoryErrors are no
longer an issue with this function. :-) Still, I always wonder how close I am
to a MemoryError (I am on a tiny Win 7 32 VM, with Python 2.7). I sometimes
check the Task Manager to see how much RAM is in use. Is there a Python way to
do something similar?
Best wishes,
Albert-Jan
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